Antimicrobial activity of gaseous Citrus limon var pompia leaf essential oil against Listeria monocytogenes on ricotta salata cheese. (May 2020)

• Record Type: Journal Article
• Authors: Fancello, Francesco; Petretto, Giacomo L.; Marceddu, Salvatore; Venditti, Tullio; Pintore, Giorgio; Zara, Giacomo; Mannazzu, Ilaria; Budroni, Marilena; Zara, Severino
• Is Part Of: Food microbiology. Volume 87(2020)
• Publication Date: 2020-05
• Subjects: Hurdle technology -- Listeria monocytogenes -- Ricotta salata -- EO gas -- Citral -- Refrigeration temperature; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2019.103386
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: Contamination by Listeria monocytogenes is a particularly challenging problem in the food industry due to the ability of the bacterium to develop under conditions normally used for food preservation. Here, we show that the gaseous phase of Citrus limon var p ompia leaf essential oil (hereafter PLEO) exerts specific anti - Listeria activity on ricotta salata cheese stored at 5 °C. The synergic effect of gaseous PLEO treatment and refrigeration was first confirmed in vitro on L. monocytogenes strains treated for 3 h with gaseous PLEO and then stored at 5 °C. Ricotta cheese was then inoculated with L. monocytogenes strains and subjected to hurdle technology with different concentrations of gaseous PLEO. Cell counts revealed gaseous PLEO to exert a bactericidal effect on L. monocytogenes 20600 DSMZ and a bacteriostatic effect on a mix of L. monocytogenes strains. Scanning and transmission electron microscopy analyses of L. monocytogenes cells suggested that gaseous PLEO targets the bacterial cell wall and plasma membrane. Chemical analyses of the liquid and vapor phases of PLEO indicated linalyl acetate to be the predominant compound, followed by limonene and the two isomers of citral, whereas EO composition analysis, although generally in line with previous findings, showed the presence of linalyl acetate for the first time. Solid-phase microextraction coupled with gas chromatography confirmed the presence of all crude oil components in the headspace of the box. Highlights: The antimicrobial activity of gaseous PLEO is increased when combined with refrigeration temperature. The antimicrobial activity of the gaseous PLEO varies between single and mixed Listeria strains. Bacterial cell wall and plasma membrane are putative targets of the PLEO. Gaseous PLEO shows no activity against resident mesophilic and lactic bacteria. PLEO may be considered a natural alternative to synthetic antimicrobials.